The present invention is directed to an improved riveting tool adapted for use in setting blind or hollow rivets.
The expression "blind riveting" is used herein to denote a procedure in which a hollow rivet is inserted through a hole in the work. The rivet is set at one side of the work by application of a pull to the rivet mandrel.
The invention is particularly directed to the type of riveting tool that is purely mechanical in nature and which includes one or more handles providing sufficient mechanical advantage to the operator by hand. Since considerable force is required to set the rivet, the design of the actuating mechanism is such as to produce a high mechanical advantage to create the desired force. However, in many cases this mechanical advantage produces very little pulling and several operations of the actuating mechanisms are required before the mandrel is pulled a sufficient amount to set the rivet. In addition, the attempts to produce sufficient mechanical advantage together with a sufficient degree of pulling of the mandrel has resulted in complicated actuating elements comprising a system of links and levers. Previous designs have tended to make the riveting tool cumbersome and difficult to operate, as well as making the tool difficult to manufacture, assemble and, thereby more expensive.
Mechanical hand-operated riveting tools of the prior art generally comprise a pulling device movable relative to a main body. The pulling device includes jaw elements comprise one or more handles pivotally attached to the body and connected to the pulling device through linkage elements. Examples of this type of riveting tool are shown in the U.S. Pat. Nos. to Luce 2,399,442 issued Apr. 30, 1946 and Henshaw 3,548,627 issued Dec. 22, 1970. While the construction shown and described in these two patents provides an adequate mechanical advantage for the actuating elements, there are some disadvantages. The multiplicity of pivotal connections produces mechanical losses. The fact that the handles are pivoted on the body at points outside of the main portion of the body reduces the amount of effective motion produced by the handle for a given handle opening. The connecting links are connected to the pulling device at points on opposite sides of the longitudinal axis of the pulling. A moment arm is thereby created between the axis of the pulling device and each pivotal connection between the pulling device and one of the links. If the force exerted by each link is not perfectly synchronized, a binding action is produced between the pulling device and the corresponding portion of the body on which the pulling device moves. It is also possible to pinch one's fingers between the handles and the connecting links and between the handles or links and the body. These and other difficulties experienced with the prior art devices have been obviated by the present invention.
It is, therefore, an outstanding object of the invention to provide a riveting tool in which the links which connect the actuating lever or handles to the pulling device at a common point and preferably along the central longitudinal axis of the pulling element, so as to direct all pulling forces to a single part of the pulling device and to eliminate any moment arms which causes the binding of the pulling device on the body.
Another object of this invention is the provision of a riveting tool in which a pair of handles or actuating levers are pivotally connected to the body at a common point, providing for maximum effective motion of the handles when they are moved together in a rivet setting operation.
A further object of the present invention is the provision of a riveting tool in which the links are connected to the pulling element at a common point and the actuating levers or handles are connected to the body at a common point and both of these points are located along the central longitudinal axis of the pulling element, thereby providing maximum operating efficiency of the actuating elements.
It is another object of the instant invention to provide a riveting tool in which all of the links are pivotal connections are enclosed within a protective outwardly and rearwardly extending portion of the body for preventing injury to the user.
A still further object of the invention is the provision of a riveting tool which is simplified in design and yet is rugged and efficient in use.
It is a still further object of the invention to provide a riveting tool which is simple in construction, which is inexpensive to manufacture, and which is capable of a long life of useful service with a minimum of maintenance.
It is a further object of the invention to provide a riveting tool having sufficient mechanical advantage together with a sufficient amount of pulling motion to enable a hollow rivet to be set with one actuating motion of the handles.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.